電感是開關電源中常用的(de)元件(jian)由于電(dian)(dian)(dian)(dian)(dian)流電(dian)(dian)(dian)(dian)(dian)壓相位(wei)不同，理論上沒(mei)有(you)損耗(hao)。電(dian)(dian)(dian)(dian)(dian)感(gan)為儲能(neng)元件(jian)，與電(dian)(dian)(dian)(dian)(dian)容一(yi)起用在輸入濾(lv)波和輸出濾(lv)波電(dian)(dian)(dian)(dian)(dian)路上用來(lai)平滑電(dian)(dian)(dian)(dian)(dian)流。電(dian)(dian)(dian)(dian)(dian)感(gan)也被(bei)稱(cheng)為扼流圈特點是流過其上的(de)電(dian)(dian)(dian)(dian)(dian)流有(you)“很大的(de)慣性”。換句(ju)話說由于磁通連(lian)(lian)續特性，電(dian)(dian)(dian)(dian)(dian)感(gan)上的(de)電(dian)(dian)(dian)(dian)(dian)流必(bi)須(xu)連(lian)(lian)續否(fou)則會(hui)產生很大的(de)電(dian)(dian)(dian)(dian)(dian)壓尖峰(feng)（感(gan)性元件(jian)，如果突然(ran)斷(duan)電(dian)(dian)(dian)(dian)(dian)（電(dian)(dian)(dian)(dian)(dian)流回路被(bei)切斷(duan)），會(hui)產生很大的(de)電(dian)(dian)(dian)(dian)(dian)壓尖峰(feng)脈沖損壞與之串(chuan)聯的(de)器件(jian)，此時必(bi)須(xu)加續流二極管續流！！！）。

　　電感常被理解為開關電源輸出端中的LC濾波電路中的L（C是其中的輸出電容）。雖這樣理解是正確的，為了理解電感的設計必須深入的了解電感的行為。在降壓轉換中，電感的一端連接到DC輸出電壓另一端通過開關頻率切換連接到輸入電壓或GND。
　　Buck/Boost型開關電源隨開關管的開關，儲能電感的電流波形等價于直流IDC上加一個I(P-P)值為ΔI的交流。因而IDC成為輸出電流IO主要消耗在負載上；交流ΔI消耗在負載電容的ESR（EquationSerial Resistance）上成為輸出紋波Vripple。
　　所(suo)以紋波(bo)電(dian)(dian)(dian)流(liu)的大小(xiao)同樣會影(ying)響電(dian)(dian)(dian)感器和輸(shu)出電(dian)(dian)(dian)容的尺寸紋波(bo)電(dian)(dian)(dian)流(liu)一般設定(ding)為(wei)最大輸(shu)出電(dian)(dian)(dian)流(liu)10%～30，因此對于(yu)降(jiang)壓型電(dian)(dian)(dian)源來說流(liu)過電(dian)(dian)(dian)感的電(dian)(dian)(dian)流(liu)峰值比電(dian)(dian)(dian)源輸(shu)出電(dian)(dian)(dian)流(liu)大5%～15%之(zhi)間(jian)。